Space Shuttle Program

 

Introduction

The Space Shuttle program was the fourth human spaceflight program carried out by the U.S. National Aeronautics and Space Administration (NASA), which conducted routine transportation for Earth-to-orbit people and cargo from 1981 to 2011. Its original name, Space Transportation System (STS), was taken from a 1969 design for a system of reusable spacecraft, of which it was the only item funded for development. It flew 135 missions and transported 355 astronauts from 16 countries, several on numerous journeys.

 Space Shuttle Program

The Space Shuttle—composed of an orbiter propelled with two reusable solid rocket boosters and a disposable external fuel tank—carried up to eight astronauts and up to 50,000 lb (23,000 kg) of payload into low Earth orbit (LEO). When its mission was complete, the orbiter would reenter the Earth's atmosphere and land like a glider at either the Kennedy Space Centre or Edwards Air Force Base.

The Shuttle is the first winged crewed spacecraft to have attained orbit and landing and the only reusable crewed space vehicle to perform several missions into orbit. [a] Its missions involved carrying big cargo to various orbits, including the International Space Station (ISS), providing crew rotation for the space station, and completing service missions on the Hubble Space Telescope. The orbiter also recovered satellites and other payloads (e.g., from the ISS) from orbit and returned them to Earth, though its employment in this capacity was unusual. Each vehicle was designed with an anticipated lifespan of 100 launches, or 10 years' operational life. Original selling points for the shuttles were over 150 launches during a 15-year operational span, with a 'launch per month' projected at the peak of the programme; however, severe delays in the creation of the International Space Station never created such a high need for frequent flights.

Various shuttle concepts have been investigated since the late 1960s. The programme formally began in 1972, becoming the main focus of NASA's human spaceflight operations after the Apollo, Skylab, and Apollo-Soyuz programmes in 1975. The Shuttle was first thought of and presented to the public in 1972 as a 'Space Truck' that would, among other things, be used to build a United States space station in low Earth orbit throughout the 1980s and then be replaced by a new vehicle by the early 1990s. The stalled plans for a U.S. space station evolved into the International Space Station and were formally initiated in 1983 by President Ronald Reagan, but the ISS suffered from long delays, design changes, and cost overruns and forced the service life of the Space Shuttle to be extended several times until 2011, when it was finally retired—serving twice as long as it was originally designed to do. In 2004, according to President George W. Bush's Vision for Space Exploration, employment of the Space Shuttle was to be focused nearly completely on finishing assembly of the ISS, which was significantly behind schedule at that point.

The first experimental orbiter, Enterprise, was a high-altitude glider launched from the rear of a specially adapted Boeing 747, only for initial atmospheric landing tests (ALT). Enterprise's first test flight was on February 18, 1977, just five years after the Shuttle programme was originally begun, leading to the launch of the first space-worthy shuttle, Columbia, on April 12, 1981, on STS-1. The Space Orbiter Project terminated with its last mission, STS-135 conducted by Atlantis, in July 2011, retiring the final orbiter in the fleet. The Space Shuttle programme formally ended on August 31, 2011.

Before the Apollo 11 Moon landing in 1969, NASA began investigating space shuttle prototypes as early as October 1968. The early experiments were marked "Phase A", then, in June 1970, "Phase B", which was more detailed and specific. The major intended use of the Space Shuttle was to support the future space station, ferry a minimum crew of four and around 20,000 pounds (9,100 kg) of cargo, and be able to be promptly turned around for future trips.

Two designs emerged as front-runners. One was designed by engineers at the Manned Spaceflight Centre and championed, especially by George Mueller. This was a two-stage system with delta-winged spacecraft and was generally sophisticated. An attempt to re-simplify was made in the form of the DC-3, created by Maxime Faget, who had designed the Mercury capsule, among other vehicles. Numerous alternatives from a range of private organisations were also given, but they typically fell by the wayside as each NASA lab pushed for its own version.

All of this was taking place in the midst of other NASA teams proposing a broad variety of post-Apollo missions, a number of which would cost as much as Apollo or more [citation needed]. As each of these initiatives struggled for funding, the NASA budget was at the same time severely constricted. Three were eventually delivered to Vice President Agnew in 1969. The shuttle project got to the top, partly thanks to the tireless agitation of its supporters [citation needed]. By 1970, the shuttle had been picked as the one significant project for the short-term post-Apollo time frame.

All Space Shuttle missions were launched from the Kennedy Space Centre (KSC) in Florida. Some private and military circumpolar space shuttle missions were planned for Vandenberg AFB in California. However, the use of Vandenberg AFB for space shuttle missions ended after the Challenger accident in 1986. The weather factors utilised for launch included, but were not limited to: precipitation, temperatures, cloud cover, lightning forecast, wind, and humidity. The Shuttle was not launched under conditions when it could have been struck by lightning.

The first completely operable orbiter was Columbia (designated OV-102), manufactured at Palmdale, California. It was delivered to Kennedy Space Centre (KSC) on March 25, 1979, and was first launched on April 12, 1981—the 20th anniversary of Yuri Gagarin's space flight—with a crew of two.

Challenger (OV-099) was delivered to KSC in July 1982, Discovery (OV-103) in November 1983, Atlantis (OV-104) in April 1985, and Endeavour in May 1991. Challenger was originally built and utilised as a structural test piece (STA-099) but was modified to a complete orbiter when this was deemed to be less expensive than transforming Enterprise from its approach and landing test configuration into a spaceworthy vehicle.

On April 24, 1990, Discovery transported the Hubble orbit telescope into orbit during STS-31.

In the course of 135 missions flown, two orbiters (Columbia and Challenger) suffered catastrophic accidents, resulting in the loss of all crew members, totaling 14 astronauts.

The accidents led to national-level inquiries and a comprehensive analysis of why they occurred. There was a lengthy pause where adjustments were made before the shuttles resumed flight. The Columbia accident occurred in 2003, but STS took more than a year off before returning to flight in June 2005 with the STS-114 mission. The previously mentioned hiatus was from January 1986 (when the Challenger accident happened) and 32 months later, when STS-26 was launched on September 29, 1988.

The longest shuttle mission was STS-80, lasting 17 days and 15 hours. The final voyage of the Space Shuttle programme was STS-135 on July 8, 2011.

Since the Shuttle's retirement in 2011, many of its original functions have been performed by an array of government and commercial vessels. The European ATV Automated Transfer Vehicle served the ISS between 2008 and 2015. Classified military missions are being conducted by the US Air Force's uncrewed spaceplane, the X-37B. By 2012, cargo to the International Space Station was already being delivered commercially under NASA's Commercial Resupply Services by SpaceX's partially reusable Dragon spacecraft, followed by Orbital Sciences' Cygnus spacecraft in late 2013. Crew service to the ISS is now supplied by the Russian Soyuz, and since 2020, the SpaceX Dragon 2 crew capsule has been flown on the company's reusable Falcon 9 rocket as part of NASA's Commercial Crew Development programme. Boeing is also developing the Starliner capsule for ISS crew service, although it has been delayed after its December 2019 uncrewed test flight failed. For trips beyond low Earth orbit, NASA is creating the Space Launch System and the Orion spacecraft, part of the Artemis programme.

Space Shuttle missions have included:

Early in the development of the Space Shuttle, NASA predicted that the programme would cost $7.45 billion ($43 billion in 2011 dollars, adjusting for inflation) in development and non-recurring expenses and $9.3 million ($54 million in 2011 dollars) per mission. Early estimates for the cost to transfer payload to low-Earth orbit were as low as $118 per pound ($260/kg) of payload ($635/lb or $1,400/kg in 2011 USD), based on marginal or incremental launch costs and assuming a 65,000 pound (30 000 kg) payload capacity and 50 launches per year. A more reasonable prediction of 12 flights per year for the 15-year service life combined with the original development expenses would have resulted in a total cost projection for the programme of around $54 billion (in 2011 currency).

The overall cost of the actual 30-year service life of the Shuttle programme through 2011, adjusted for inflation, was $196 billion. The specific breakdown between non-recurring and recurrent costs is not accessible, although, according to NASA, the average cost to launch a Space Shuttle as of 2011 was roughly $450 million per mission.

NASA's budget for 2005 allocated 30%, or $5 billion, to space shuttle operations; this was cut in 2006 to a proposal of $4.3 billion. Non-launch expenditures account for a considerable part of the programme budget. For example, from fiscal years 2004 to 2006, NASA spent roughly $13 billion on the Space Shuttle programme, even though the fleet was grounded in the aftermath of the Columbia accident and there were a total of three launches during this period of time. In fiscal year 2009, the NASA budget allocated $2.98 billion for five launches to the programme, including $490 million for "programmememe integration", $1.03 billion for "flight and ground operations", and $1.46 billion for "flight hardware" (which includes maintenance of orbiters, engines, and the external tank between

Per-launch costs can be measured by dividing the overall cost over the life of the project (including buildings, facilities, training, salaries, etc.) by the number of launches. With 135 missions and a total cost of US$192 billion (in 2010 dollars), this gives nearly $1.5 billion per launch during the course of the Shuttle programme. A 2017 analysis indicated that delivering one kilogramme of cargo to the ISS on the Shuttle cost $272,000 in 2017 dollars, double the cost of Cygnus and three times that of Dragon.

NASA utilised a management concept known as success-oriented management throughout the Space Shuttle programme, which was defined by historian Alex Roland in the aftermath of the Columbia accident as "hoping for the best". Success-oriented management has since been explored by various experts in the subject.

In the course of 135 missions flown, two orbiters were destroyed, with the loss of crew totaling 14 astronauts:

There was also one abort-to-orbit and some deadly incidents on the ground during launch preparations.

STS-51-L (Challenger, 1986) 

Close-up film footage of Challenger during its final launch on January 28, 1986, clearly demonstrates that the difficulties began due to an O-ring failure on the right solid rocket booster (SRB). The hot plume of gas seeping from the failing joint caused the collapse of the external tank, which eventually resulted in the orbiter's disintegration due to high aerodynamic stress. The tragedy resulted in the loss of all seven astronauts on board. Endeavour (OV-105) was manufactured to replace Challenger (using structural spare parts originally meant for the other orbiters) and delivered in May 1991; it was first launched a year later.

After the loss of Challenger, NASA halted the Space Shuttle project for over two years, making various safety changes recommended by the Rogers Commission Report, which included a redesign of the SRB joint that failed in the Challenger accident. Other safety changes included a new escape system for use when the orbiter was in controlled flight, improved landing gear tyres and brakes, and the reintroduction of pressure suits for Shuttle astronauts (these had been discontinued after STS-4; astronauts wore only coveralls and oxygen helmets from that point on until the Challenger accident). The Shuttle programme continued in September 1988 with the launch of Discovery on STS-26.

The incidents damaged not just the technical design of the orbiter but also NASA. Quoting some proposals given by the post-Challenger Rogers commission:

Recommendation I: The problematic solid rocket motor joint and seal must be changed. This might be a new design eliminating the joint or a modification of the current junction and seal. ... the Administrator of NASA should invite the National Research Council to organise an impartial Solid Rocket Motor design oversight committee to implement the Commission's design recommendations and oversee the design process. Recommendation II: The Shuttle Programme Structure should be examined. NASA should support the transition of qualified astronauts into agency executive posts. Recommendation III: NASA and the key shuttle contractors should examine all Criticality 1, 1R, 2, and 2R items and hazard analyses. Recommendation IV: NASA should establish an Office of Safety, Reliability, and Quality Assurance to be headed by an Associate Administrator, reporting directly to the NASA Administrator. Recommendation VI: NASA must make efforts to increase landing safety. The tyre, brake, and nosewheel systems must be enhanced. Recommendation VII: Make all attempts to create a crew escape method for use during controlled gliding flights. Recommendation VIII: The nation's reliance on the shuttle as its major space launch capability generated unrelenting pressure on NASA to raise the flight rate. .. NASA must establish a flying rate that is consistent with its resources.

STS-107 (Columbia, 2003) 

The Shuttle programme operated accident-free for seventeen years and 88 missions after the Challenger disaster, until Columbia broke up on reentry, killing all seven crew members on February 1, 2003. The eventual cause of the accident was a piece of foam separating from the external tank minutes after liftoff and striking the leading edge of the orbiter's left wing, puncturing one of the reinforced carbon-carbon (RCC) panels that covered the wing edge and protected it during reentry. As Columbia reentered the atmosphere at the end of an otherwise normal mission, hot gas infiltrated the wing and destroyed it from the inside out, causing the orbiter to lose control and disintegrate.

After the Columbia accident, the International Space Station operated on a skeleton crew of two for more than two years and was serviced primarily by Russian spacecraft. While the "Return to Flight" mission STS-114 in 2005 was successful, a similar piece of foam from a different area of the tank was shed. Although the debris did not strike Discovery, the programme was halted once again for this reason.

The second "Return to Flight" mission, STS-121, launched on July 4, 2006, at 14:37 (EDT). Two earlier missions were scrubbed due to prolonged thunderstorms and high winds around the launch pad, and the launch took place over concerns from its top engineer and safety director. A five-inch (13 cm) break in the foam insulation of the exterior tank provided cause for concern; however, the Mission Management Team gave the go-ahead for the launch. This trip expanded the ISS crew to three. Discovery touched down successfully on July 17, 2006, at 09:14 (EDT) on Runway 15 at Kennedy Space Centre.

Following the success of STS-121, all subsequent missions were completed without major foam problems, and the construction of the ISS was completed (during the STS-118 mission in August 2007, the orbiter was again struck by a foam fragment on liftoff, but this damage was minimal compared to the damage sustained by Columbia).

The Columbia Accident Investigation Board, in its report, noted the reduced risk to the crew when a shuttle flew to the International Space Station (ISS), as the station could be used as a safe haven for the crew awaiting rescue in the event that damage to the orbiter on ascent made it unsafe for reentry. The board proposed that for the following voyages, the shuttle would always orbit around the station. Prior to STS-114, NASA Administrator Sean O'Keefe declared that all future flights of the Space Shuttle would go to the ISS, precluding the possibility of executing the final Hubble Space Telescope servicing mission, which had been scheduled before the Columbia accident, despite the fact that millions of dollars worth of upgrade equipment for Hubble were ready and waiting in NASA warehouses. Many dissenters, including astronauts [who?], lobbied the NASA administration to reconsider permitting the project, but initially the director stayed fast. On October 31, 2006, NASA announced clearance of the launch of Atlantis for the fifth and final shuttle servicing mission to the Hubble Space Telescope, scheduled for August 28, 2008. However, SM4/STS-125 eventually launched in May 2009.

One repercussion of Columbia was that subsequent crewed launch vehicles, particularly the Ares I, had a greater priority on crew safety compared to other issues.

The Space Shuttle retirement was announced in January 2004. President George W. Bush revealed his Vision for Space Exploration, which called for the retirement of the Space Shuttle once it completed construction of the ISS. To guarantee the ISS was properly assembled, the contributing partners identified the need for 16 further assembly trips in March 2006. One extra Hubble Space Telescope servicing mission was approved in October 2006. : III-352 Originally, STS-134 was to be the final Space Shuttle mission. However, the Columbia accident resulted in more orbiters being prepared for launch in the event of a rescue mission. As Atlantis was ready for the final launch-on-need mission, the decision was reached in September 2010 that it would fly as STS-135 with a four-person crew that could remain on the ISS in the event of an emergency. STS-135 launched on July 8, 2011, and landed at the KSC on July 21, 2011, at 5:57 a.m. EDT (09:57 UTC). From then until the launch of Crew Dragon Demo-2 on May 30, 2020, the US launched its astronauts aboard Russian Soyuz spacecraft.

Following each orbiter's final mission, it was processed to make it safe for viewing. The OMS and RCS systems utilised provided the greatest threats due to their toxic hypergolic propellant, and most of their components were permanently removed to prevent any dangerous outgassing. Atlantis is on exhibit at the Kennedy Space Centre Visitor Complex in Florida. Discovery is at the Udvar-Hazy Centre, Virginia, III-451. Endeavour is on exhibit at the California Science Centre in Los Angeles, III-457, while Enterprise is displayed at the Intrepid Sea-Air-Space Museum in New York, III-464. Components from the orbiters were delivered to the US Air Force, the ISS programme, and the Russian and Canadian governments. The engines were removed to be utilised on the Space Launch System, and spare RS-25 nozzles were added for exhibition purposes.

Out of the five fully functional shuttle orbiters produced, three remain. Enterprise, which was utilised for atmospheric test flights but not for orbital flight, had several pieces pulled out for use on the other orbiters. It was then aesthetically refurbished and was on exhibit at the National Air and Space Museum's Steven F. Udvar-Hazy Centre until April 19, 2012. Enterprise was transferred to New York City in April 2012 to be displayed at the Intrepid Sea, Air, and Space Museum, whose Space Shuttle Pavilion debuted on July 19, 2012. Discovery replaced Enterprise in the National Air and Space Museum's Steven F. Udvar-Hazy Centre. Atlantis constituted part of the Space Shuttle Exhibit at the Kennedy Space Centre tourist complex and has been on display there since June 29, 2013, following its renovation.

On October 14, 2012, Endeavour performed a record 12-mile (19-kilometre) drive on city streets from Los Angeles International Airport to the California Science Centre, where it has been on exhibit in a temporary hangar since late 2012. The transit from the airport took two days and necessitated massive street closures, the removal of over 400 city trees, and extensive labour to raise power lines, level the street, and temporarily remove street signs, light posts, and other obstructions. Hundreds of volunteers and fire and police officials helped with the trip. Large groups of fans waited on the streets to view the shuttle as it passed through the city. Endeavour, along with the last flight-qualified external tank (ET-94), is now on exhibit at the California Science Centre's Samuel Oschin Pavilion (in a horizontal configuration) until the completion of the Samuel Oschin Air and Space Centre (a proposed expansion to the California Science Centre). Once transported, it will be permanently displayed in launch configuration, replete with authentic solid rocket boosters and an external tank.